Electric-arc lamp.



J. T. H. DEMPSTER.

ELEGTEIG ARC LAMP. APPLIOATION FILED MAY 31,1902.

Patented Jan. 10, 1911.

'mvenfioi. John THDempsfier.

WiCnessas.

UNITED STATES PATENT OFFICE.

JOHN T. H. DEMPSTER, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL EL'E TRIG COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC-ARC LAMP.

tain new and useful Improvements in Electric-Arc Lamps, of which the following is a through the coyer and the upp r end of specification.

My present invention is intended more especially for use in connection with are lamps of thattype in which the arc is rendered luminous by reason of the materials used in forming the electrodes, though it is to be understood of course that various features thereof are of value in other relations as well.

Among other featuresmy invention provides means for preventing discoloration of the arcanclosmg ,globe by reason of SOll(l matter given off from the arc in the form of smoke, and also provides means whereby the arc is rendered steady and free from the flickering or swaying back and forth ordinarily present in luminous arcs of any. considerable length.

The novel features which I believe characterize my invention I have pointed out with particularity in the appended claims while in the following description, which is to be taken in connection wlth the accompanying drawings, I have set forth in detail certain embodiments of my invention.

In the drawings Figure 1 represents one embodiment of my-invention and Fig. 2 a modification.

The frame-work of the lamp, as indicated in Fig. 1, includes two disks or plates 1 and 2 held apart from each other and secured in position by means of connecting rods such as at 3 and 4. From the lower plate 1 depend two rods 5 and 6 carrying at the lower end a crossbar 7 which supports the lower carbon'holder 8 and the are-inclosi'ng globe 9 carried thereby. This arc-inclosing globe, which is closed at the bottom by its reception in the holder 8, is provided at its top with a perforated cover 10. This cover is of cylindrical shape provided with a recess on its outer edge so as to fit. into the top of the arc-inclosing globe. Passing through the central portion of the cover is a draft tube or chimney member 11, the lower end of which projects downward a eertain distance Specification of Letters Patent.

ney member 12 provided at its lower ond w th :1 dated portion 13 forms a telescopic oint with the tube 11. The flared tu which may be made of metal, or of inica or glass so as to transmit light, is sup orted by small cross-bars or rods 14: from t e rod 15 carrying the upper electrode. This upper electrode rod 15 is controlled by means of a e" mg it in place. Another draft tube or chint- Patented Jan-.10; 1911;

Application filed May 31, 1902. Serial No. 109,583.

solenoid 16 carried by cross bars 18 and 19 J fixed to the upper ends of two tubes 20 and 21"which pass through openings in the upper plate 2 of the lanipbframe and arosecured thereto as indicated.

\Vithin the solenoid 16 is a tubular arma ture 22 of magnetic material suspended by means ofa' spring 23 the upper end of which is secured at the top of an upwardly extend iug tube 24 carried by the cross-bar 18. The

lower end of the armature isfastened to a tubular guiding member 25 of non-mags .nctic "material to which, are attached the clutch mechanism 26, the d'ash-pots-Z'T and H the upper electrode rod 15 as indicated. The i rod 15 moves in the tubes 22 and 25 'according as its position is adjusted relatively to the clutch 26. 1

The purpose of the telescopic tube 11 and 12 above referred to is to produce an up ward draft of air in the vicinity of the are and to cause this draft to be directed inward in the neighborhood of the to of the are so as to steady the latter an prevent it from swaying or flickering back and forth. To provide an ingress for the air, a series of holes or perforations may be made m the top plate or cover 10, two of these holes being indicated in the cross-sectional view at 28.

producing a partial vacuum which draws fresh air into the arc-inclosing globe through the openings 28 in the cover of the globe. The heated air draft rising through the The heat of the arc causes the air to ascend through the telescopic tubes, thus telescopic tubes removes from the same and places. In this manner the dropping of such products into the globe is prevented and at the same time the tip of the upper electrode iscleaned' of insulating deposits thereon, which. if allowed to form, would make the starting of the are uncertain. The air draft then enters the space between the plates 1 and 2 constituting portions of the lamp frame-work and this space is inclosed by a cylindrical shell 29 so as to form a chamber from the upper portions of which extend the tubes and 21. The heated air passes from this chamber up through the tubes, thereby inducing a strong down-draft along the walls of-the globe through the openings 28 and producing an up-draft along the upper e'nd of'the are, which has the effect before mentioned of preventing flicker ng or .SWayHW' back and forth of the are and also of witdidrawing from the arc-inclosin chamber, from the chimney entrance and from the tip of the upper electrode, as soon as they are formed, any fumes or solid products givenoff by the arc in the form of smoke or otherwise. If it is desired to prevent the lamp from giving off this smoke into the-outer atmosphere, I provide the chamber between plates-1 and 2 with what I may perhaps term filtering screens indicated in cross-section at 30. As the upward draft int-he lamp draws the smoke or other products from the are through the meshes of these screens the solid matter is deposited therein, thereby preventing the same from being discharged by the air drafts into the outer air. In'order to render the upward draft. through the telescop'ic tubes the most effective in steadying the are, I find that the upper floating electrode 31 should be arranged with reference to the flared portion 13 of'the tube 12 so that the lower ends are substantially on a level with each other. This may be readily done by adjusting the osition of the tube by a eet-screw or other evice 32 acting on the electrode carrying rod 15.

It will be observed that in the construe tion described, the draft tube or chimney passage, which may be regarded as formed of sections consisting of the tubes 20, 21, bhamber 29, and tubes 11 and l2, extends ,from the u per 'end of the are to practically lthe top Q the lamp-structure. \This argrangement insures a relatively powerful natural draft which is found to be highly beneficial in lamps ofi this characterf *I prefer to use electrodes formed with a mixture of the magnetic oxid of lIOIll; as a basis with. certain other materials such as maggliesia, borates or thelike. As electrodes of t is composition waste away very slowly it is\seldom necessary to vary the adjust.- mentiof the upper electrodes with respect to the\tube 12. the upper electrode instead of wasting away ma actually increase slightly in length.-

Iii the lamp which I have described above,

Indeed it may happen that the solenoid 16 is intended to be connected in shunt with the electrodes, which electrodes a re provided with a series resistance to steady the are. This series resistance 21 may be wound about butinsulated from the drafttubes 20 and '21 and by heating the same increase the draft. The circuit connections 'of this lamp are as follows: The current enters the lamp by conductor 17, proceeds to and through the resistance windings 21, 21, which are. connected by conductor 48, and then by flexible conductor 49 totheupper electrode, then to the lower electrode, and

out by conductor 53. At a point 50 the conductor 49 is tapped by a shunt-wire 51,

which leads to' one terminal of solenoid 16,

the other terminal of which is connected duetor 53.

The use of the shunt feed lamp of the type described has the advantage that the electrodes do not dro together when the current is shut off which with certain compositions of electrodes is distinctly an advantage, since if they were permitted in many cases to remain to ether whlle hot,

they would weld or stick ast to each other. When electrodes of this character are used.

the electrodes separated when the current is turned off and such an arrangement is indicated in Fig. 2. In this figure the series controlling magnet is indicated at 33 and its armature carrying the mechanism of the upper electrode at 34. armature, or a part carried thereby, is a small rack-35 having a pawl or lock 36 urged toward it by means of a spring 37 and away from it by means of a magnet 38 acting upon its armature 39 which carries the pawl. This magnet may be in a circuit of extremely high resistance across the electrodes of the lamp so that if the arc goes out or the current is turnedoff. the magnet is deeuergized and the pawl 36 byengaging the of the electrode tl. This flared tube is sup-' ported from the electrode rod 42 by means of radially arranged members or pins 16 so as to permit the heated air from the are to flow upward through. the tube and into the outer air. This upward draft operates to draw air into the arc-inclosing globe through an annular space which is purposely left by shunt wire 52 with the out-going con- Attached to the between the tube 45 and the walls of the arc-inclosin globe 40 as indicated.

What I c aim as new anddesire to secure by Letters Patent of the United States, is,

1. In an electric arc lamp, the combination of fume producin electrodes arranged vertically, one above the other, and means for directing a flow of air or .gases laterally toward and vertically along the upper end of the arc, whereby the arc is steadied and insulating. deposit upon the upper electrode is reduced and removed therefrom.

2. In an electric arc lamp, the combination of electrodes arranged vertically, one above the other, anda draft tube open at both ends'directly surrounding the upper electrode and arranged with its lower open end substantially on a level with the lower end ofthe electrode.

3. In an electric arc lamp, the com'binaarran ed with its lower end substantially on.

a leve with the lower open end of the electrode, whereby the walls of the globe are 'swe )t by a down-draft and the upper-electr e by an up-draft.

1. In an electric arc lamp, the combination of electrodes arranged vertically end to-end, an arc-inclosing globe, a top' cover for said globe having air ingress openings, and a draft-directing chimney open at both endsand with its lower end substantially on a level with the lower end of the upper elec- =trode within the globe and communicating with the external atmosphere.

5. The combination of electrodes arranged end-to-end, one above the other, an arc-inclosing globe, a conduit for producing a draft through said globe laterally toward and vertically along the upper end of the arc, and an intermediate 11n1rifying chamber in the draft conduit, wirreby the arc is steadied,insulating deposit on the upper draft through said globe laterally toward and vertically along the upper end of the are, an intermediate purifying chamber in the conduit, and depositing screens in said chamber,

7. In an arc lamp, a stationary lower electrode, a movable upper electrode, a holder therefor, a chimney member open at both ends secured to the electrode holder and terminating at its lower open end substantially on a level with the lower end of the upper electrode. a

8. In an arc lamp, a movable upper electrode, and a draft tube or chimney comprising two sections, one of said sections being stationary and communicating with the external atmosphere, and the other section movable with the upper electrode and terminating at its lower open end substantially on a level with the lower end of'the upper electrode.

9. In an arc lamp, a movable upper electrode, a holder therefor, and an open-ended sectional chimney member adjustably secured thereto. I

10. In an arc lamp, a lower stationary electrode, an upper floating electrode, and a.

chimney member open at bothends secured to the floating electrode with its lower open end (in substantially the same levelas the lower end of the floating electrode.

11. In an arc lamp, a movable upper elec- JOIIN '1. II. DEMISTER.

W'itnesscs hcnamun 1%. Hunt, ll'nmcn ()nronn. 

